1. Field of the Invention
The present invention relates to an improvement in a microwave circuit package for sealing therein microwave circuitry having monolithic microwave integrated circuits (hereinafter referred to as MMICs), as well as to ribbons and bonding wires for use in fabricating the microwave circuit package.
2. Description of the Related Art
Conventionally, bonding wires having uniform diameters along their lengths, ribbons of uniform thickness and/or mesh ribbons, have been used for mounting high-frequency devices to a metallic substrate in a microwave circuit package.
Japanese Patent Laid-Open Publication No. HEI 1-300546 discloses a microwave circuit package in which electrostatic capacity is provided externally of an area of an MMIC chip by forming a dielectric layer between a metallic substrate and a biasing direct current (DC) terminal.
In such a microwave circuit package, discontinuity of impedance is likely to arise at places where ribbons and bonding wires are provided. As a result, it is likely that components such as MMICs vary in their bare characteristics after mounting or assemblage thereof, leading to deteriorated characteristics of the components.
Certain occasions arise wherein it is desired that a microwave circuit package be fabricated using metallic substrates, MMICs and bonding wires which are altered in their materials, while rendering the microwave circuit package to be compatible with a separate microwave circuit package fabricated using the same components but not involving such changes in material, by varying the post-mounting high-frequency characteristics of the MMIC and so forth.
The post-mounting high-frequency characteristics of the MMICs may be varied by changing the lengths of the ribbons and bonding wires. However, connection through the bonding wires requires of the latter to be gently curved in a proper manner. In addition, length alteration of the bonding wires is limited due to the limited space within the microwave circuit package. Another possible approach would be to change the spacing between the components such as the MMICs to allow alteration of the lengths of the ribbons. However, the space alteration is also limited and hence is not an effective solution.